Connecticut provides a property tax exemption for "Class I" renewable energy systems* and hydropower facilities that generate electricity for private residential use. The exemption is available for systems installed on or after October 1, 2007, that serve single-family homes or multi-family dwellings limited to four units.* In addition, "any passive or active solar water or space heating system or geothermal energy resource" is exempt from property taxes, regardless of the type of facility the system serves.

Connecticut municipalities are also authorized, but not required, to offer a property tax exemption for (1) the amount by which the assessed valuation of an active solar energy heating or cooling system installed after October 1, 1976, and before October 1, 2006, exceeds the assessed value of a conventional heating or cooling system, and (2) the amount by which the assessed valuation of a passive or hybrid solar energy heating or cooling system installed on or after April 20, 1977, exceeds the valuation at which such real property would be assessed if built using conventional construction techniques. Such assessments are in effect for the first 15 years following construction or addition to a building.

An exemption claim must be filed with the assessor or board of assessors in the town in which the property is placed on or before the first day of November in the applicable assessment year. Applications are not required each year as long as no major alterations are made to the renewable energy system. Contact your local tax assessor's office for more information.

* A "Class I renewable energy source" is defined as “(A) energy derived from solar power, wind power, a fuel cell, methane gas from landfills, ocean thermal power, wave or tidal power, low emission advanced renewable energy conversion technologies, a run-of-the-river hydropower facility provided such facility has a generating capacity of not more than five megawatts, does not cause an appreciable change in the river flow, and began operation after July 1, 2003, or a sustainable biomass facility with an average emission rate of equal to or less than .075 pounds of nitrogen oxides per million BTU of heat input for the previous calendar quarter, except that energy derived from a sustainable biomass facility with a capacity of less than five hundred kilowatts that began construction before July 1, 2003, may be considered a Class I renewable energy source, or (B) any electrical generation, including distributed generation, generated from a Class I renewable energy source.”